The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 08, 1994
Filed:
Feb. 28, 1992
Ichiro Nakamura, Katsuta, JP;
Haruo Watanabe, Chiyoda, JP;
Tsuyoshi Ogasawara, Ishioka, JP;
Katsuharu Shuto, Chiyoda, JP;
Eiichi Sasaki, Katsuta, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
A hydraulic elevator comprises a car, a hydraulic jack to drive the car, a hydraulic pump, and control means for controlling a flow rate of fluid flowing to or from the hydraulic jack thereby to control movement of the car. The control means comprises a main valve constructed so as to allow fluid the flow from the pump into the hydraulic jack when a pressure of the fluid is higher than a predetermined value thereby to effect upward running of the car, and to check a fluid flow from the hydraulic jack when the pressure of the fluid from the pump is less than the predetermined value, and valve control means including a plurality of pilot valves for controlling, when the pressure of the fluid from the pump is less than the value, the main valve to open and close, and wherein the valve control means controls the closing operation of the main valve along at least two different patterns.